Re: [RFC] Make grafts versionable

From: Linus Torvalds <torvalds@osdl.org>
Date: Nov 21, 2005, 21:35 UTC
Message-ID: <Pine.LNX.4.64.0511211326110.13959@g5.osdl.org>
In-Reply-To: <43823654.2060904@zytor.com>

On Mon, 21 Nov 2005, H. Peter Anvin wrote:

> 
> Now, CVS has a reserved namespace (CVSROOT/) for things under version control
> which are still significant to CVS.  The logical equivalent to git would be to
> have .git/ be such a namespace, if it makes sense.

Well, there's two reasons for disallowing git from tracking it's own .git directory:

 - it protects against people doing somethin glike

	git-update-cache --add -- $(find . -type f | cut -c3..)

   and finding the pre-existing files in ".git"

   This used to literally be how I imported trees into git. These days, 
   you can just do it with "git-ls-files --others", and in fact that is 
   exactly what "git add" does, so now you can just do

	git add .

   and be done with it - without getting that ".git" directory by mistake.

   So that _old_ reason may not be as valid any more.

However, there's one fundamental reason:

 - if you have a file in ".git", that implies that even a "raw git repo" 
   would have versions matter, since technically such a file would be 
   inside the "raw" part. And that I find to be confusing. One of the 
   whole points of a raw git repo is that because it doesn't have anything 
   that is version-controlled and checked out, none of the branches or 
   tags are special, and nothing needs to be updated when you push to such 
   a repo.

   Now, if you have files in .git, suddenly that fundamental nature of a 
   raw repository is no longer clear.

In general, making any internal git data versionable is very confusing. So you make the grafts file versionable - that suddenly means that different branches may have different parents for the same commit. And that depending on which branch you have checked out, git-fsck-cache may result in an error, or it may not. That's _nasty_, in my opinion.

So I much prefer to say: everything under ".git" is not versionable, for the fundamental reason that the files under .git are "global" to that git repository.

And I think .git/grafts in particular makes no sense to version.

If you want to track a git "grafts" file, you can do it as another git repository and a symlink.

		Linus